Standard Specification for
Steel, Closed-Impression Die Forgings for General Industrial
Use
1This standard is issued under the fixed designation A 521; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers untreated and heat-treated steel, closed-impression die forgings (Note 1) for general industrial use.
NOTE 1—For the definition of a forging, refer to Definition A 509.
1.2 The classes of forgings are as follows, the choice depending on design and stress or service to be imposed:
1.2.1 Class CA—Untreated, carbon steel forgings,
1.2.2 Classes CC, CC1, and CE—Annealed, normalized and tempered, carbon steel forgings,
1.2.3 Class CF—Normalized and tempered carbon steel forgings,
1.2.4 Class CF1—Double normalized and tempered carbon steel forgings,
1.2.5 Class CG—Quenched and tempered, or normalized, quenched and tempered carbon steel forgings,
1.2.6 Class AA—Annealed, normalized, or normalized and tempered alloy steel forgings,
1.2.7 Classes AB and AC—Normalized and tempered alloy steel forgings, and
1.2.8 Classes AD, AE, AF, AG, and AH—Normalized, quenched, and tempered alloy steel forgings.
NOTE 2—The appendix tables list recommended tolerances for a
number of materials other than those covered by the above classes. The tables are for information only and the purchaser must define the condition in which he desires forgings made from materials not described above.
1.3 The values stated in inch-pound units are to be regarded as the standard.
2. Referenced Documents
2.1 ASTM Standards:
A 29/A 29M Specification for Steel Bars, Carbon, Hot-Wrought, Special Quality2
A 322 Specification for Steel Bars, Alloy, Standard Grades2
A 370 Test Methods and Definitions for Mechanical Testing of Steel Products3
A 509 Definition of Terms Relating to Steel Forging4 A 576 Specification for Steel Bars, Carbon, Hot-Wrought,
Special Quality2
A 711 Specification for Steel Forging Stock2
E 10 Test Method for Brinell Hardness of Metallic Materi-als5
E 23 Test Method for Notched Bar Impact Testing of Metallic Materials5
E 94 Guide for Radiographic Testing6
3. Terminology
3.1 Definitions of Terms Specific to This Standard: 3.1.1 annealing—the forgings shall be reheated to a tem-perature which produces an austenitic structure and then cooled slowly. A furnace charge thus treated is termed an annealing charge.
3.1.2 cooling prior to heat treatment—after forging and before reheating for heat treatment, the forgings shall be cooled to provide substantially complete transformation of austenite. 3.1.3 normalizing—the forgings shall be reheated to a temperature which produces an austenitic structure and then withdrawn from the furnace and cooled in air. A furnace charge thus treated is termed a normalized charge.
3.1.4 quenching—the forgings shall be reheated to a tem-perature which produces an austenitic structure and then quenched in a suitable liquid medium by spraying or immer-sion. A group thus treated is termed a quenching charge.
3.1.5 tempering—the forgings shall be reheated to and held at the proper temperature, which will be below the austenitic transformation range, and then cooled under suitable condi-tions. A furnace charge thus treated is termed a tempering charge.
4. Ordering Information
4.1 The purchaser shall specify in the inquiry, contract, and order the class of steel desired; and any exceptions, modifica-tions, or agreements with regard to the provisions of this specification.
1
This specification is under the jurisdiction of ASTM Committee A-1 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.06 on Steel Forgings and Billets.
Current edition approved Sept. 10, 1996. Published July 1997. Originally published as A 521 – 64. Last previous edition A 521 – 76 (1992)e1.
2Annual Book of ASTM Standards, Vol 01.05.
3
Annual Book of ASTM Standards, Vol 01.03.
4Discontinued—see 1982 Annual Book of ASTM Standards, Vol 01.05. 5
Annual Book of ASTM Standards, Vol 03.01.
6Annual Book of ASTM Standards, Vol 03.03. AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428 Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
5. Process
5.1 The steel shall be made by any or all of the following processes: open-hearth, electric-furnace, or basic-oxygen.
6. Discard
6.1 Sufficient discard shall be made to secure freedom from piping and undue segregation.
7. Forging Manufacture
7.1 Manufacturing practice shall be in accordance with accepted commercial procedures designed to produce forgings free from harmful surface discontinuities, roughness, excessive scale, fins, indications of overheating, or other injurious discontinuities. The manufacturer may be required to certify that furnaces used for all heating operations for forging and heat treating are controlled to minimize scaling and decarbur-ization and equipped with suitable controls.
8. Chemical Requirements
8.1 The steel shall conform to the requirements for chemical composition listed in Table 1 on alloy steel bars in Specifica-tion A 322 or in Table 1 on carbon steel bars in SpecificaSpecifica-tion A 576. Other limits may be specified for carbon steels using the ranges and limits in Table 2 of Specification A 576 or for alloy steels in Table 4 of A 29/A 29M.
8.2 The limits of elements other than those listed above may be agreed upon by the manufacturer and purchaser.
9. Dimensional Tolerances
9.1 Tolerances for impression die forgings (Appendix X1) shall apply.
10. Finish
10.1 The forgings shall be free of injurious discontinuities.
11. Heat Analysis
11.1 An analysis of each heat of steel shall be made by the manufacturer to determine the percentages of carbon, manga-nese, phosphorus, sulfur, and silicon; also the alloying ele-ments agreed on in accordance with Section8. This analysis shall be made from a test ingot taken during the pouring of the heat. The chemical composition thus determined shall be reported to the purchaser or his representative, and the percent-ages of phosphorus and sulfur, and also the alloying elements shall conform to the requirements specified and agreed upon in Section 8.
12. Product Analysis
12.1 An analysis may be made by the purchaser from a forging representing each heat. Drillings for analysis may be taken from the forging or from a full-size prolongation, at any point midway between the center and surface when solid, or between the inner and outer surfaces of the wall when bored; or turnings may be taken from the test specimen. The chemical composition thus determined shall not vary from the require-ments specified in Section 8 by more than the amounts prescribed for product analysis in Specification A 711.
13. Tensile Properties
13.1 The material shall conform to the requirements for
tensile properties prescribed in Table 1 when tested in accor-dance with the latest issue of Test Methods and Definitions A 370.
13.2 The yield strength shall be determined by the offset method, using an offset value of 0.2 % of the gage length, or by the total extension under load method, using an extension value of 0.005 in./in. (0.5 %) for Classes AD and AE, 0.006 in./in. (0.6 %) for Classes AF and AG, and 0.007 in./in. (0.7 %) for Class AH.
13.3 Tests for acceptance shall be made after final heat treatment of the forgings.
14. Number of Tests
14.1 One tension test shall be made for each heat of steel for each heat treat charge. For untreated forgings (Class CA) no tension tests shall be made except when specified in the purchase order and then one tension test shall be run on each heat.
14.2 If any test specimen fails because of mechanical reasons, such as testing equipment failure or improper speci-men preparation, it may be discarded and another specispeci-men taken.
14.3 For the purpose of tests of heat-treated forgings, the necessary extra forgings shall be provided. When it is imprac-ticable to provide extra forgings for test purposes, test bars may be made from the billet or bar, provided they are given approximately the same reduction and heat treatment as the forgings and also represent the maximum cross section of the forging.
15. Retests
15.1 If the results of the mechanical tests of any test lot do not conform to the requirements specified, the manufacturer may reheat treat such lot, but not more than three additional times unless authorized by the purchaser, and retests shall be made in accordance with Section 14.
15.2 If the percentage of elongation of any tension test specimen is less than that specified in Table 1 and any part of the fracture is outside of the middle half of the gage length, a retest shall be allowed.
15.3 If a test specimen fails to meet the specified mechani-cal property requirements due to a discontinuity other than a rupture, crack, or flake, a retest shall be allowed.
16. Test Specimen
16.1 Location, size, and number of test specimens shall be specified by the purchaser. Unless otherwise stated in the contract or purchase order, test bars may be separately forged or swaged from the same bars, billets, or blooms used in manufacture of the forgings. The percentage reduction given the forged tests bars shall not be greater than the minimum amount of reduction given the forging itself. The test bars shall be heat treated with the forgings they represent. The manufac-turer may elect to submit an extra forging in lieu of forged test bars.
16.2 Unless otherwise specified, the axis of the specimen shall be located at any point midway between the center and the surface of solid forgings or at any point midway between the inner and outer surfaces of the wall of hollow forgings, and
shall be parallel to the direction of maximum metal flow. 16.3 The specimens shall be machined to the form and dimensions shown in Test Methods and Definitions A 370 for the standard or subsize round tension test specimens.
17. Cleaning
17.1 The forgings shall be furnished in a scale-free condi-tion. Unless otherwise specified, the manufacturer may clean by acid pickling, grit blasting, sand blasting, or other abrasive method.
18. Marking
18.1 Marking of forgings shall be specified by the pur-chaser.
19. Inspection
19.1 Unless otherwise specified, the inspector representing the purchaser shall have entry, at all times while work on the contract of the purchaser is being performed, to those parts of the manufacturer’s plant that concern the manufacture of the material ordered. The manufacturer shall afford the inspector,
without charge, all reasonable facilities to satisfy him that the material is being furnished in accordance with this specifica-tion. All tests (except product analysis) and inspection shall be made at the place of manufacture prior to shipment, unless otherwise specified, and shall be conducted so as not to interfere unnecessarily with the operation of the plant.
20. Rejection
20.1 Any rejection based on tests made in accordance with Section 10 shall be reported to the manufacturer within 60 days from the receipt of samples by the purchaser.
20.2 Material that shows injurious discontinuities subse-quent to its acceptance at the manufacturer’s plant will be rejected, and the manufacturer shall be notified.
21. Certification
21.1 A certification shall be made the basis of acceptance of the material. This shall consist of a copy of the manufacturer’s test report stating that the material has been sampled, tested, and inspected in accordance with the specified provisions of the specification. Each certification so furnished shall be signed TABLE 1 Tensile Requirements
Class Solid Diameter or Thickness, in. (mm)
Bored Wall Thickness in. (mm) Tensile Strength, min, ksi (MPa) Yield Strength, min, ksi (MPa) Elongation in 2 in. or 50 mm, min, % Reduction of Area, min, % Over Not Over Over Not Over
AA (Annealed, normalized, or ... 12 (305) ... ... 80 (550) 50 (345) 24 40 normalized, and tempered) 12 (305) 20 (508) ... ... 80 (550) 50 (345) 22 38 AB (Normalized and tempered) ... 7 (178) ... 4 (102) 80 (550) 55 (380) 26 52 7 (178) 20 (508) 4 (102) 71⁄2 (191) 80(550) 55(380) 24 50
AC (Normalized and tempered) ... 7 (178) ... 4 (102) 90 (620) 60 (415) 22 44 7 (178) 20 (508) 4 (102) 71⁄2 (191) 90 (620) 58 (400) 21 42
AD (Normalized, quenched, and ... 7 (178) ... 31⁄2 (89) 96 (655) 70 (485) 20 50
tempered) 7 (178) 10 (254) 1⁄2 (89) 5 (127) 90 (620) 65 (450) 20 50
AE (Normalized, quenched, and ... 7 (178) .... 31⁄2 (89) 105 (725) 80 (550) 20 50
tempered) 7 (178) 10 (254) 31⁄2 (89) 5 (127) 100 (690) 75 (520) 19 50
10 (254) 20 (508) 5 (127) 8 (203) 95 (655) 70 (485) 19 50 AF (Normalized, quenched, and ... 4 (102) ... 2 (51) 125 (860) 105 (725) 16 50 tempered) 4 (102) 7 (178) 2 (51) 31⁄2 (89) 115 (795) 96 (655) 16 45
7 (178) 10 (254) 31⁄2 (89) 5 (127) 110 (760) 85 (585) 16 45
AG (Normalized, quenched, and ... 4 (102) ... 2 (51) 145 (1000) 120 (830) 15 45 tempered) 4 (102) 7 (178) 2 (51) 31⁄2 (89) 140 (965) 115 (795) 14 40
7 (178) 10 (254) 31⁄2 (89) 5 (127) 135 (930) 110 (760) 13 40
AH (Normalized, quenched, and ... 4 (102) ... 2 (51) 170 (1175) 140 (965) 13 40 tempered) 4 (102) 7 (178) 2 (51) 31⁄2 (89) 165 (1140) 135 (930) 12 35
7 (178) 10 (254) 31⁄2 (89) 5 (127) 160 (1105) 130 (895) 11 35
(No Physical Requirements except as covered by 13.1.)
CA (Untreated) ... ... ... ... ... ... ... ...
CC (Annealed, normalized, or ... 12 (305) ... ... 60 (415) 30 (205) 25 36 normalized, and tempered) 12 (305) ... ... ... 60 (415) 30 (205) 24 36 CC1 (Annealed, normalized, or ... 12 (305) ... ... 66 (455) 33 (230) 23 36 normalized and tempered) 12 (305) 20 (508) ... ... 66 (455) 33 (230) 22 34 CE (Annealed, normalized, or ... 8 (203) ... ... 75 (520) 37 (290) 24 40 normalized and tempered) 8 (203) 12 (305) ... ... 75 (520) 37 (290) 22 35
12 (305) 20 (508) ... ... 75 (520) 37 (290) 20 32
20 (508) ... ... ... 75 (520) 37 (290) 19 30
CF (Normalized and tempered) ... 8 (203) ... ... 80 (550) 40 (275) 22 36
8 (203) 12 (305) ... ... 80 (550) 40 (275) 21 33
12 (305) 20 (508) ... ... 80 (550) 40 (275) 20 31
CF1 (Double normalized and tempered) ... 8 (203) ... ... 85 (585) 44 (305) 25 40
8 (203) 12 (305) ... ... 83 (570) 43 (295) 23 37
12 (305) 20 (508) ... ... 83 (570) 43 (295) 22 35
CG (Quenched, and tempered or ... 4 (102) ... 2 (51) 90 (620) 55 (380) 20 39 normalized, quenched and tempered) 8 (203) 7 (178) 2 (51) 31⁄2 (89) 85 (585) 50 (345) 20 39
7 (178) 10 (254) 31⁄2 (89) 5 (127) 85 (585) 50 (345) 19 37
by an authorized agent of the supplier or manufacturer.
22. Repair of Forgings
22.1 Forgings shall not be weld repaired. Grinding to
remove surface discontinuities will be permitted unless other-wise specified by the purchaser.
SUPPLEMENTARY REQUIREMENTS
One or more of the following supplementary requirements shall apply only when specified by the purchaser in the inquiry, contract, and order. Details of these supplementary requirements shall be specified by purchaser.
S1. Magnetic Particle Test
S1.1 When magnetic particle inspection of forgings is required, the specific method, the areas to be inspected, and the standards of acceptability shall be specified by purchaser.
S2. Grain Flow
S2.1 When a specific pattern of grain flow is required by the purchaser, a sample forging shall be sectioned as specified. The section shall be ground and subjected to acid etching, using the type of acid, temperature and time of etching agreed upon to reveal flow lines. The section may be preserved using a coating of mineral oil or clear lacquer.
S3. Microscopical Test
S3.1 When microscopical examination is specified, the steel shall be inspected by utilizing samples cut from the undistorted portion of tension test specimens. Requirements for number of microscopical tests, grain size, cleanliness, or microstructure shall be specified by purchaser.
S4. Impact Test
S4.1 When impact tests are required, the type of specimen,
number of tests, and standards for acceptance shall be specified by the purchaser. Reference shall be made to Test Method E 23.
S5. Ultrasonic Tests
S5.1 When ultrasonic tests are required, details as to proce-dure and standards shall be specified by the purchaser.
S6. Radiographic Tests
S6.1 When radiographic tests are required, the number of tests, location, and ASTM standards of acceptance shall be specified by the purchaser. Reference shall be made to Practice E 94.
S7. Brinell Hardness
S7.1 When hardness is required, Brinell hardness tests of sample forgings from each furnace charge of heat treated forgings shall be conducted. Number of samples per charge shall be specified by the purchaser. Reference should be made to the latest issue of Test Method E 10.
APPENDIXES
(Nonmandatory Information)
X1. FORGINGS PRODUCED ON HAMMERS AND PRESSES
X1.1 Units of Measure
X1.1.1 Where direct tolerances are not provided, use Table X1.1 in converting to fractional units of measure after making computations.
X1.2 Length and Width Tolerances
X1.2.1 Length and width tolerances represent variations in
dimensions measured parallel to the fundamental parting line of the dies. Normally, they are combined with tolerances for die wear.
X1.2.1.1 Tolerance—The length and width tolerance is 60.003 in./in. and applies to all dimensions of length and width including diameters. This tolerance includes allowance for shrinkage, die sinking, and die polishing variations.
X1.2.1.2 Units of Measure—Length and width tolerances, normally combined with tolerances for die wear, are expressed as fractions of an inch, in units of1⁄32 in. or greater as shown in Table X1.1. Decimals used in computing tolerances are totaled, rounded off to two places after the decimal point, then converted to the next higher fractional unit of measure.
X1.3 Die Wear Tolerances
X1.3.1 Die wear varies according to the material forged and TABLE X1.1 Units of Measure
Dimensions, ft (m) Units of Measure to the Closest Over Under ... 2 (0.61) 1⁄32in. 2 (0.61) 5 (1.52) 1⁄16in. 5 (1.52) 10 (3.05) 1⁄8in. 10 (3.05) ... 1⁄4in.
the shape of the forging. Consequently, die wear tolerances for various materials are applied in addition to length and width tolerances on dimensions pertaining to forged surfaces only. Die wear tolerances do not apply on center-to-center dimen-sions.
X1.3.1.1 Tolerance—Die wear tolerances for all external length, width, and diameter dimensions are computed by multiplying the greatest external length or outside diameter (measured parallel to the fundamental parting line of the dies) by the appropriate factor in Table X1.2 and are then combined with plus values of length and width tolerances. Die wear tolerances on external dimensions are expressed as plus values only.
X1.3.1.2 Die wear tolerances for all internal length, width and diameter dimensions are also computed by multiplying the
greatest external length or outside diameter (measured parallel
to the fundamental parting line of the dies) by the appropriate factor in Table X1.2, but are then combined with the minus values of length and width tolerances. Die wear tolerances on
internal dimensions are expressed as minus values only.
X1.3.1.3 Allowances for die wear occurring on dimensions measured perpendicular to the fundamental parting line of the dies are included in die closure tolerances.
X1.3.1.4 Die wear tolerances, per surface, on both external and internal dimensions are one half the computed amount.
X1.3.1.5 Units of Measure—Die wear tolerances combined with length and width tolerances are expressed as fractions of an inch in units of1⁄32in. or greater as shown in Table X1.1. Decimals used in computing tolerances are totaled, rounded off to two places after the decimal point, then converted to the next higher fractional unit of measure.
X1.4 Die Closure Tolerances
X1.4.1 Die closure tolerances relate to variations in thick-ness of forgings as affected by the closing of the dies and die wear, and pertain to variations in dimensions crossing the fundamental parting line.
X1.4.1.1 Tolerance—Die closure tolerances on forgings having no portions extending more than 6 in. (152 mm) from the parting line are based on the projected area of the forging at the trim line—not including flash, but including all areas to be subsequently punched out. Except as explained in the following paragraph, they are applied as plus tolerances only and are applicable to the thickness of the forging at all sections. (See Table X1.3.)
X1.4.1.2 Tolerances on extremities of forgings extending perpendicularly more than 6 in. from the parting line include the die closure tolerance, and, in addition, a length tolerance of 60.003 in./in. This tolerance is added to that derived from Table X1.3, but applies only to such extremities.
X1.4.1.3 Units of Measure—Die closure tolerances are expressed as fractions of an inch in units of1⁄32 in. or greater. When decimals are used in computing tolerances, they are rounded off to two places after the decimal point, then converted to the next higher fractional unit of measure.
X1.5 Match Tolerances
X1.5.1 Match tolerances relate to displacement of a point in one die half from the corresponding point in the opposite die half in any direction parallel to the fundamental parting line of the dies. Match tolerances are applied separately and indepen-dently of all other tolerances. Where possible, measurements are made at areas of the forging unaffected by wearing of the dies.
X1.5.1.1 Tolerance—Match tolerances are based on weight of the forging after trimming and are expressed as fractions of an inch according to Table X1.4.
X1.5.1.2 Measuring for Match Tolerances— In cases where measurements for determining match tolerances must be made from surfaces of the forging where uneven wearing of the dies has caused surplus stock, accuracy depends on making the proper allowances for these wear-caused surpluses, and elimi-nating their influence from the computation.
X1.5.1.3 Units of Measure—Match tolerances are measured in units of1⁄64 in. or greater.
X1.6 Flash Extension Tolerances
X1.6.1 Flash extension tolerances are based on the weight of the forging after trimming and relate to the amounts of flash extension. Flash is measured from the body of the forging to the trimmed edge of the flash.
X1.6.2 Tolerance—Flash extension tolerances are ex-pressed in fractions of an inch according to Table X1.5.
X1.7 Straightness Tolerances
X1.7.1 Straightness tolerances relate to deviations of sur-faces and centerlines from the specified contour as caused primarily by manipulation of the piece in post-forging pro-cesses and, in addition, by the effects of cooling from the forging operation, both of which may produce slight and gradual variations in straightness.
X1.7.2 Since the general shape of the forging determines the effect of cooling and post-forging manipulation on straightness, four classes of shape have been selected as guides in choosing appropriate straightness tolerances. Agreement between pur-chaser and forging engineer on tolerances and inspection methods may be desirable where the forging is not easily classified according to shape and may be subject to a combi-nation of straightness tolerances. Straightness tolerances are applied independently of, and in addition to, all other toler-ances.
X1.7.3 It is contemplated that, at times, straightening op-erations may be required in order to achieve the tolerances indicated in the following text. These tolerances are not TABLE X1.2 Die Wear Tolerances
Materials Factor (per inch)
Carbon 0.004 Low Alloy 0.005 400 Series Stainless 0.006 300 Series Stainless 0.007 Super Alloy 0.008 Titanium 0.009 Refractory Material 0.012 2014 Aluminum 0.004 7075 Aluminum 0.007 Magnesium 0.006 Brass 0.002 Copper 0.002
intended to apply to refractory alloys, high-density alloys, titanium, and some stainless steels. Straightness tolerances for forgings of such materials are best determined on the basis of each individual forging design, since the configuration substan-tially influences the tendency of a forging to deviate from the specified contour. Straightness tolerances for these special
forgings are commonly agreed upon by buyer and seller in advance of production.
X1.7.4 Units of Measure—Straightness tolerances are ex-pressed as fractions of an inch in units of1⁄32in. or greater, as shown in Table X1.1. Decimals used in computing tolerances are rounded off to two places after the decimal point, then TABLE X1.3 Die Closure Tolerances
NOTE 1—Tabulated figures are plus values only, expressed in inches.
Materials Area at the Trim Line Flash not included, expressed in in.2(cm2)
10 (65) and un-der Over 10 to 30 (65 to 194), incl Over 30 to 50 (194 to 323), incl Over 50 to 100 (323 to 645), incl Over 100 to 500 (645 to 3225), incl Over 500 to 1000 (3225 to 6450), incl Over 1000 (6450)
Carbon, low alloys 1⁄32 1⁄16 3⁄32 1⁄8 5⁄32 3⁄16 1⁄4
400 series stainless 1⁄32 1⁄16 3⁄32 1⁄8 3⁄16 1⁄4 5⁄16
300 series stainless 1⁄16 3⁄32 1⁄8 5⁄32 3⁄16 1⁄4 5⁄16
Super alloys, titanium 1⁄16 3⁄32 1⁄8 3⁄16 1⁄4 5⁄16 3⁄8
Aluminum, magnesium 1⁄32 1⁄32 1⁄16 3⁄32 1⁄8 3⁄16 1⁄4
Refractory alloys 3⁄32 1⁄8 5⁄32 3⁄16 1⁄4 5⁄16 3⁄8
TABLE X1.4 Match Tolerances
NOTE 1— Tabulated figures are amounts of displacement, expressed in inches, of a point in one die-half from the corresponding point in the opposite
die-half in any direction parallel to the parting line of the dies.
Materials Weights of Forgings After Trimming, lb (kg) Less than 2 (0.91) Over 2 to 5 (0.91 to 2.3), incl Over 5 to 25 (2.3 to 11.3), incl Over 25 to 50 (11.3 to 22.7), incl Over 50 to 100 (22.7 to 45.4), incl Over 100 to 200 (45.4 to 90.6), incl Over 200 to 500 (90.6 to 226.5), incl Over 500 to 1000 (226.5 to 453.0), incl Over 1000 (453.0)
Carbon, low alloys customarily negoti- 1⁄64 1⁄32 3⁄64 1⁄16 3⁄32 1⁄8 5⁄32 3⁄16
Stainless steels ated with pur- 1⁄32 3⁄64 1⁄16 3⁄32 1⁄8 5⁄32 3⁄16 1⁄4
Super alloys, titanium chaser 1⁄32 3⁄64 1⁄16 3⁄32 1⁄8 5⁄32 3⁄16 1⁄4
Aluminum, magnesium 1⁄64 1⁄32 3⁄64 1⁄16 3⁄32 1⁄8 5⁄32 3⁄16
Refractory alloys 1⁄16 3⁄32 1⁄8 5⁄32 3⁄16 1⁄4 5⁄16 3⁄8
TABLE X1.5 Flash Extension Tolerance NOTE 1—Tabulated figures are ranges of flash extension, expressed in inches.
Weights of Forgings After Trimming, lb (kg)
Materials Carbon & Low Alloy Stainless Super Alloys and
Titanium Aluminum & Magnesium Refractory Alloy 10 (4.5) and under 0 to1⁄32 0 to1⁄16 0 to1⁄16 0 to1⁄32 0 to1⁄8 Over 10 to 25 (4.5 to 11.3), incl 0 to1⁄16 0 to3⁄32 0 to3⁄32 0 to1⁄16 0 to3⁄16 Over 25 to 50 (11.3 to 22.7), incl 0 to3⁄32 0 to1⁄8 0 to1⁄8 0 to3⁄32 0 to1⁄4 Over 50 to 100 (22.7 to 45.4), incl 0 to1⁄8 0 to3⁄16 0 to3⁄6 0 to1⁄8 0 to5⁄16 Over 10 to 200 (45.4 to 90.6), incl 0 to3⁄16 0 to1⁄4 0 to1⁄4 0 to3⁄16 0 to3⁄8 Over 200 to 500 (90.6 to 226.5), incl 0 to1⁄4 0 to5⁄16 0 to5⁄16 0 to1⁄4 0 to1⁄2 Over 500 to 1000 (226.5 to 453.0), incl 0 to5⁄16 0 to3⁄8 0 to3⁄8 0 to5⁄16 0 to5⁄8 Over 1000 (453.0) 0 to3⁄8 0 to1⁄2 0 to1⁄2 0 to3⁄8 0 to3⁄4
TABLE X1.6 Classes of Shapes NOTE 1—For use in selecting appropriate Straightness Tolerances.
Class Shape of Forging Examples
A Elongated—Length dimensions great in relation to width and height long connecting rods, shafts, levers, etc.
B Flat, relatively thin disc, plates, etc.
C Flat, relatively thin, with appreciable protrusion at right angles to the parting line
wear plates, crawler track shoes, disc with hub, etc. D Massive block-type forgings with neither length, nor width, nor
thick-ness being predominant
converted to the next higher fractional unit of measure. X1.7.5 Tolerances and Applications (Table X1.6):
X1.7.5.1 Class A Shapes (Elongated—Long in relation to width and height) Tolerance: 0.003 in./in. of the greatest dimension.
X1.7.5.2 Class B Shapes (Flat, Relatively Thin) Tolerance—Straightness tolerance for Class B shapes as shown
in Table X1.7 below.
X1.7.5.3 Class C Shapes (Thin, Flat Shapes with
Appre-ciable Protrusion at Right Angles to the Parting Line) Tolerance—Straightness tolerance on the flat disc portion of
Class C shapes is computed first. It is considered separately from the tolerance on the protruding portion and is determined in an identical manner as for Class B shapes using Table X1.7. Straightness tolerance on protuberance is 0.003 in./in. of length.
X1.7.5.4 Class D Shapes (Massive, Block-type Forgings)
Tolerance—Since departures from the specified configuration
are seldom caused by subsequent handling, straightness toler-ances are not provided. Where tolertoler-ances are desired, agree-ment between purchaser and forging engineer is normally reached before production proceeds.
X1.8 Surface Tolerances
X1.8.1 Surface tolerances relate to depth of dressouts and scale pits on the forging, based on purchaser’s specification or drawing.
X1.8.1.1 Tolerances and Conditions—Localized dressouts or scale pits are commonly allowed on surfaces to be finish machined unless purchaser’s specification or drawing states otherwise. Where purchaser specifies stock for machining, dressouts or scale pits are commonly permitted to within1⁄16in. (1.59 mm) of the finished surface or to within one-half of the stock allowance, whichever is smaller.
X1.8.1.2 Where surfaces of forgings are intended for use in “as forged” condition, dressouts or scale pits are commonly permitted on these surfaces to a depth equal to 1⁄2 of the die closure tolerance.
X1.9 Draft Angle Tolerances
X1.9.1 Draft angle tolerances apply to all draft angles, relate to variation from draft angle specifications, and are commonly measured as an addition to tolerances for die wear.
X1.9.1.1 Tolerance—Draft angle tolerances are +2° and −1° on all draft angles, unless modified by prior agreement between buyer and seller.
X1.10 Finish Allowances for Machining
X1.10.1 Finish allowance refers to the amount of material that is to be machined from the forging to obtain the finished part. Forging dimensions are commonly analyzed indepen-dently, with consideration given to all applicable tolerances, in making certain that a minimum desired clean-up exists after the forging is completed. (See Table X1.8.)
X2. FORGINGS PRODUCED ON FORGING MACHINES (UPSETTERS)
X2.1 Length Tolerances
X2.1.1 Length tolerances relate to variations in dimensions measured parallel to the axis of the stock and apply to all
intermediate and over-all dimensions of length except flange thickness dimensions and internal length (gap) dimensions TABLE X1.7 Straightness Tolerances, Class B Shapes
Materials Area at the Trim Line, expressed in in.2(cm2) Flash not included
10 (65) and under Over 10 to 30 (65 to 194), incl Over 30 to 50 (194 to 323), incl Over 50 to 100 (323 to 645), incl Over 100 to 500 (645 to 3225), incl Over 500 to 1000 (3225 to 6450), incl Over 1000 (6450)
Carbon, low alloy 1⁄32 1⁄16 3⁄32 1⁄8 5⁄32 3⁄16 1⁄4
400 series stainless 1⁄32 1⁄16 3⁄32 1⁄8 3⁄16 1⁄4 5⁄16
300 series stainless 1⁄16 3⁄32 1⁄8 5⁄32 3⁄16 1⁄4 5⁄16
Aluminum, magnesium 1⁄32 1⁄32 1⁄16 3⁄32 1⁄8 3⁄16 1⁄4
TABLE X1.8 Finish Allowances
Greatest Dimension Minimum Finish Stock per Surface Over, in. (mm) But Not Over,
in. (mm) ... 8 (203) 1⁄16 8 (203) 16 (406) 3⁄32 16 (406) 24 (610) 1⁄8 24 (610) 36 (914) 5⁄32 36 (914) ... 3⁄16
between flanges (see X2.2) . Length tolerances include allow-ances for die wear, shrinkage, die sinking and die polishing variations.
X2.1.2 Tolerance—Length tolerances are plus values only, expressed in fractions of an inch according to Table X2.1.
X2.2 Flange Tolerances
X2.2.1 Flange tolerances relate to variations in flange thick-ness measured parallel to the axis of the stock. When more than one flange is formed, these tolerances also apply to the dimension (gap) between flanges. Flange tolerances are applied separately and independently of other tolerances.
X2.2.1.1 Tolerance—Tolerances for flange thickness and dimensions (gaps) between flanges are such that the effect is to add stock on both internal and external dimensions. The amount of flange tolerance is dependent on the flange diameter (see Table X2.2).
X2.2.1.2 When two flanges are formed, the tolerance on the dimension (gap) between them is a minus tolerance only, with a value identical to the thickness tolerance for the flange nearest the unforged stem.
X2.2.1.3 Flange tolerances are shown in Table X2.2.
X2.3 Diameter Tolerances
X2.3.1 Diameter tolerances relate to variation in dimensions measured perpendicularly to the axis of the stock, and are applied separately for each of a forging’s diameters and only to those diameters formed in the heading tool or dies.
X2.3.2 Diameter tolerances are commonly applied and mea-sured in a plane other than that described by the parting line of the forging.
X2.3.3 Permissible variations in diameter on unforged stem
portions of the forging are commonly governed by steel mill
tolerances. Tolerance provisions for shear-cut ends and slight irregularities in diameter on the unforged stem caused by grip dies are commonly determined by special agreement between buyer and seller.
X2.3.4 These tolerances apply only to forgings with circular shapes. Tolerances for non-circular forgings are customarily determined by special agreement between buyer and seller in advance of production.
X2.3.4.1 Tolerance—Tolerances for all external forged di-ameters are expressed as plus tolerances only, according to Table X2.3.
X2.3.4.2 Tolerances for internal diameters of holes formed by the heading tool are commonly +0 in.; −1⁄16in.
X2.4 Match Tolerances
X2.4.1 Match tolerances relate to the amount of die dis-placement in a direction parallel to the parting line of the grip dies. These tolerances are applied independently of, and in addition to, all other tolerances.
X2.4.2 Tolerance—Match tolerances are expressed as frac-tions of an inch in units of1⁄64in. or greater, according to Table X2.4. They are based on the weight of the forging exclusive of the weight of the unforged stem. The weight of the stem is deducted from the weight of the forging before Table X2.4 is used.
X2.5 Concentricity Tolerances
X2.5.1 Concentricity tolerances apply to contours formed by the heading tool and relate to variations of the axis of the contour from the axis of the stock. This tolerance is commonly applied only to contours of a depth not less than one diameter. Concentricity tolerances are applied independently of, and in addition to, match tolerances.
X2.5.1.1 Tolerance—Concentricity tolerances are ex-pressed in fractions of an inch as total indicator readings (TIR), according to Table X2.5.
X2.6 Straightness Tolerances
X2.6.1 Straightness tolerances relate to deviations of the centerline of the stem and body of the forging from the true centerline as caused by manipulation of the piece after forging, and by the effects of cooling from the forging operation—both of which may produce slight and gradual variations in straight-ness.
X2.6.1.1 Tolerance—Straightness tolerances on the original bar stock as provided by the material suppliers commonly apply.
TABLE X2.1 Length Tolerances
NOTE 1—Tabulated figures are plus values only and apply to overall
and intermediate dimensions of length, except flange thickness and gap dimensions.
Length Dimensions Tolerances Over,
in. (mm)
But Not Over, in. (mm) Intermediate Length, in. (mm) Over-All Length, in. (mm) ... 31⁄8(79) 1⁄32(0.79) 1⁄16(1.58) 31⁄8(79) 61⁄4(159) 1⁄16(1.58) 3⁄32(2.38) 61⁄4(159) 95⁄16(236) 3⁄32(2.38) 1⁄8 (3.18) 95⁄16(236) 121⁄2(318) 1⁄8 (3.18) 1⁄8 (3.18) 121⁄2(318) 155⁄8(397) 5⁄32(3.97) 5⁄32(3.97) 155⁄8(397) 183⁄4(476) 3⁄16(4.76) 3⁄16(4.76) 183⁄4(476) 217⁄8(557) 7⁄32(5.56) 7⁄32(5.56) 217⁄8(557) 25 (635) 1⁄4 (6.35) 1⁄4 (6.35)
25 (635) ... Commonly determined by special agree-ment between buyer and seller in ad-vance of production
TABLE X2.2 Flange Tolerances NOTE 1—Based on diameters of flange (or flanges) formed.
Diameters Tolerances
Over, in. (mm)
But Not Over, in. (mm) Plus, in. (mm) MinusA ... 7 (178) 7 (178) ... 1⁄16(1.59) 3⁄32(2.38) ... ...
ADetermined individually as defined in X2.2.
TABLE X2.3 Tolerances on Forged Diameters
Diameters Tolerances
Over, in. (mm)
But Not Over, in. (mm) Plus, in. (mm) Minus ... 2 (51) 1⁄32(0.79) ... 2 (51) 7 (178) 1⁄16(1.59) ... 7 (178) ... 3⁄32(2.38) ...
X2.7 Draft Angle Tolerances
X2.7.1 When draft angles are required on a forging, the size of the angles is generally dependent on the contour of the forging and is therefore commonly determined by agreement between buyer and seller.
X2.7.2 Draft angle tolerances apply to all draft angles and relate to variation from draft angle specifications.
X2.7.3 Tolerance—Draft angle tolerances are +2° and −1° on all draft angles, unless modified by prior agreement between buyer and seller.
X2.8 Radii Tolerances
X2.8.1 Radii tolerances relate to variation from purchaser’s radii specifications on all fillet radii and on corner radii where draft is not subsequently removed by trimming or punching.
X2.8.1.1 Tolerance—Radii tolerances are plus or minus one-half the specified radii, except where corner radii are affected by subsequent removal of draft, in which case the minus tolerance is commonly modified to allow a square corner to be formed.
X2.9 Surface Tolerances
X2.9.1 Surface tolerances relate to depth of dressouts and scale pits on the forging, based on purchaser’s specification or drawing.
X2.9.1.1 Tolerances and Conditions—Localized dressouts or scale pits are commonly allowed on surfaces to be finish machined unless purchaser’s specification or drawing states otherwise. Where purchaser specifies stock for machining, dressouts or scale pits are commonly permitted to within1⁄16in. (1.59 mm) of the finished surface or to within one-half of the stock allowance, whichever is smaller.
X2.9.1.2 Where surfaces of forgings are intended for use in “as forged” condition, dressouts or scale pits are commonly permitted on these surfaces to a depth equal to 1⁄2 of the die closure tolerance.
X2.10 Finish Allowances for Machining
X2.10.1 Finish allowance refers to the amount of material that is to be machined from the forging to obtain the finished part. Forging dimensions are analyzed independently, with consideration given to all applicable tolerances, in making certain that a minimum desired clean-up exists after the forging is completed.
X2.10.1.1 Allowances—Table X2.6 indicates finish allow-ances commonly applied.
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TABLE X2.4 Match Tolerances
NOTE 1—Tabulated figures are amounts of die displacement in a direction parallel to the parting line of the grip dies, expressed in inches.
Materials Weights of Forgings, lb (kg)
10 (4.54) and under Over 10 to 25 (4.54 to 11.3), incl Over 25 to 50 (11.3 to 22.7), incl Over 50 to 100 (22.7 to 45.4), incl Over 100 to 200 (45.4 to 90.6), incl Over 200 to 500 (90.6 to 226.5), incl
Carbon and low alloy 1⁄64 1⁄32 3⁄64 1⁄16 3⁄32 1⁄8
Stainless steels 1⁄32 3⁄64 1⁄16 3⁄32 1⁄8 5⁄32
Super alloys and titanium 1⁄32 3⁄64 1⁄16 3⁄32 1⁄8 5⁄32
Aluminum and magnesium 1⁄64 1⁄32 3⁄64 1⁄16 3⁄32 1⁄8
Refractory alloys 1⁄16 3⁄32 1⁄8 5⁄32 3⁄16 1⁄4
TABLE X2.5 Concentricity Tolerances on Holes
Depth of Hole Total Indicator Reading (Tolerance) Over,
in. (mm)
But Not Over, in. (mm)
... 8 (203) 1⁄8 TIR
8 (203) 12 (305) 5⁄32TIR
12 (305) ... 3⁄16TIR
TABLE X2.6 Finish Allowances
Greatest Diameter Minimum Finish Stock per Surface,
in. (mm) Over,
in. (mm)
But Not Over, in. (mm)
... 2 (51) 1⁄16(1.58)
2 (51) 8 (203) 3⁄32(2.38)
